1. Field of the Invention
The present invention relates to an apparatus for developing a photographic film, and more particularly to an improved film developing apparatus with which the condition of a developing solution is monitored for controlling the developing solution.
2. Discussion of Related Art
Conventional film developing apparatuses for developing photographic films include a developing section, a drying section, etc. Currently, so-called automatic developing apparatuses which include a CPU for controlling various. factors which affect the developing process are widely used. In the use of such automatic developing apparatuses, a developing solution must be controlled with the greatest care.
Controlling of a processing solution in the film developing section is generally carried out by the use of a so-called control strip. The control strip is an undeveloped film which has predetermined reproductive characteristics and has been exposed to light under standard exposure conditions in which the intensity of light, exposure time and the characteristics of light are previously determined. After the control strip is developed, the density of the film is measured to determine the exhaustion degree of the developing solution.
Since the control strip must be processed in dark, it is put in a dark box, called "control strip holder" in a darkroom. The control strip is then set in a receiving inlet of the developing section of a film developing apparatus together with a holder therefor.
As described above, in conventional film developing apparatuses, controlling of developing solution is carried out based on the results obtained by developing the control strip housed in the control strip holder. However, the control strip holder involves drawbacks in that the mechanism for receiving the control strip is not simple due to the necessity of light-shielding, causing a troublesome operation for loading the control strip into the control strip holder.
Moreover, at the time of setting a control strip holder in a film developing apparatus, complicated operation is required because of the requirement of complete shielding of light. For checking the condition of the developing solution, it is required to stop the general development processes, and then to set a control strip holder containing a control strip in the film processing apparatus.
In many cases, however, developing solutions are controlled without the use of a control strip, because the loading of the control strip into the control strip holder and the setting of the control strip holder into the film developing apparatus are cumbersome, and the control strip must be specially prepared as a material for controlling the developing solution. In such cases, controlling of the developing solutions is carried out by a well-trained operator who intuitively determines the condition of the developing solution based on the frequency of processing, operation cycle time of the film developing apparatus, and the quality of the processed negative films.
In such, there arise fears that a misjudgment of the operator may happen in controlling the developing solution, which will allow deteriorated developing. Further, hiring of well-trained operators is against the automation and simplification of processing.